My household standards are low, believe me, but I wouldn't do this. Isn't washing up liquid one of those things where you're supposed to go to hospital if you consume it? Not sure I would confidently know it was too small amount for that. Is it not better just to order a pizza for once?

Tendon - My DM used to wash plates and dishes with washing up liquid, then put them on the drying rack without rinsing. God knows how much washing up liquid we ingested over the years, but all of us made it through! I think you'd have to take in a fair amount for it to do obvious damage.